The present invention relates to a fuel injection system for internal combustion engines and, more particularly, to an engine rapid acceleration restricting device provided in such a fuel injection system.
A fuel injection system of the kind referred to above, for example, a fuel injection system including a fuel injection pump provided therein with a governor of all speed type, is generally arranged such that, when the rotational speed of the engine reaches a value set by depressing operation of the accelerator pedal, the amount of fuel to be injected into the engine is regulated under the action of the governor so as to control the rotational speed of the engine to the set value. Because of such arrangement, however, as the accelerator pedal is rapidly depressed, the regulating action of the governor does not effectively function for a short period of time immediately after the rapid depression of the accelerator pedal. This results in a rapid increase in the amount of fuel fed into the engine and in a rapid increase in the rotational speed of the engine. However, the speed of a vehicle having the engine mounted thereon cannot follow such rapid increase in the rotational speed of the engine. This raises such problems that jerky or wobbly vibration occurs on the vehicle, causing uncomfortable driving feeling, as well as such a problem that the amount of fuel into the engine is made excessive to cause incomplete combustion. In order to avoid such problems, Japanese Provisional Utility Model Pubulication (Kokai) No. 57-30338 and Japanese Provisional Patent Publication (Kokai) No. 60-53627 have proposed to employ a dash pot which is associated with a tension lever for controlling the action of the govenor so as to restrict and retard the moving speed of the tension lever with respect to the speed of the depressing operation of the accelerator pedal.
In the above-mentioned prior art, however, the dash pot is located in a narrow space within a pump housing of the fuel injection pump, making it difficult to provide a sufficient operating stroke for the dash pot and thus preventing the dash pot from exhibiting a sufficient damping function. Further, as the temperature of the fuel within the pump housing rises during operation of the engine, the damping effect of the dash pot is considerably reduced.
Additionally, in the above-mentioned prior art, it is so arranged that when the accelerator pedal is depressed, a reaction force produced by the damping action of the dash pot is directly transmitted to the accelerator pedal. This causes the operator to feel an unpleasant resistance, and makes the depressing feeling uncomfortable.